DC motor driving method for reducing adverse RF interferences and application to a vehicle lighting or signalling device

a technology of dc motor and adverse interference, applied in the direction of motor/generator/converter stopper, dynamo-electric converter control, instruments, etc., can solve the problem of unfavorable electromagnetic radiation, high length of cables, and inability to reduce the effect of electromagnetic radiation

Inactive Publication Date: 2005-07-28
VALEO VISION SA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The patent text describes a method for controlling a control circuit for an electric motor to reduce unfavourable electromagnetic radiation. The method involves determining the operating phase of the control circuit during which unfavourable electromagnetic emissions exist and varying the control parameter of the circuit to reduce the emissions. This can include changing the frequency, pulse width, or pulse amplitude of the control signal. The method can also involve selecting a control parameter or performing an averaging operation over a predetermined range of frequencies. The technical effect of this invention is to reduce the negative impact of electromagnetic radiation on the performance and control of automobile functions, without adding significant cost or labor.

Problems solved by technology

According to a first measure, in fact, it is known that the unfavourable electromagnetic radiation is to a major extent emitted on the connectors and on the connection cables, whose length may in certain cases be high.
Moreover, such devices comprise more components and a problem of insulation in the cables is encountered.
These three measures have the drawback of requiring the fitting of additional components, which increase the material cost of the automobile function for which the anti-EMC protection is designed.
In addition, when the function is manufactured and during its installation, and then during the maintenance of the vehicle, the provision of these measures presents a labour cost which must be as small as possible since anti-EMC protection is not a positive function but serves solely to reduce an intrinsic defect in an automobile function control technique.

Method used

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  • DC motor driving method for reducing adverse RF interferences and application to a vehicle lighting or signalling device
  • DC motor driving method for reducing adverse RF interferences and application to a vehicle lighting or signalling device
  • DC motor driving method for reducing adverse RF interferences and application to a vehicle lighting or signalling device

Examples

Experimental program
Comparison scheme
Effect test

first embodiment

[0059]FIG. 4 depicts two graphs characteristic of two possible strategies applied in the invention.

[0060] The control applied in one example embodiment already mentioned with the help of FIG. 1 uses the Pulse Width Modulation scheme in which a first part of a period with an active value and then a second part of the said period with an inactive state are determined. Particularly in the case of an operating mode of the device of FIG. 1 in the state of maintaining the position of the stepping motor 3, the pulse width modulation control by the control circuit 1 is effected with a repetition of constant width. This situation greatly generates unfavourable radiation which the application of the method of the invention makes it possible to reduce.

[0061]FIG. 4 shows the time t on the X-axis and the instantaneous value Im of the maintaining current generated by the control circuit on the Y-axis. The amplitude of the time on the X-axis has been reduced to a kth period of repetition of the c...

second embodiment

[0078]FIG. 6 is a diagram of a circuit implementing the invention.

[0079] The same control circuit as that of FIG. 5 is used. According to the invention, the control variation taught by the method of the invention is executed by varying the time constant of a circuit charging the reference terminal of the integrated control circuit 8 as already described with the help of FIG. 5. To this end, a variable resistor 35 is connected between a DC supply voltage 37 and the aforementioned terminal 30. The variable resistor 35 has an ohmic value which can be determined by a control applied to a control electrode 36 connected to a computer implementing the control method of the invention. Such a resistor can be formed on the basis of a programmable memory such as the products from the company Xicor. As a result the resistance value R34 affects an RC cell composed of the variable resistor 34 and the aforementioned capacitor 31. As a result the integrated pulse width modulation module of the cont...

third embodiment

[0080]FIG. 7 is a diagram of a circuit implementing the invention.

[0081] The same control circuit as that of FIG. 5 or 6 has been used. Such a circuit does however have a terminal supplying DC voltage 41, the variation of which is used to determine a variation in response of the cycle ratio and / or the frequency of the pulse width modulation scheme produced in the aforementioned integrated module.

[0082] To this end, the local varying of the bias voltage or supply voltage of the control circuit 1 is effected by means of a variable resistor 40, similar to the resistor 35 already described. This controllable resistor 40 comprises a control electrode 42 which can therefore be controlled from the control computer, a suitable output port of which can be connected to the control electrode 42.

[0083] Naturally, these control variation strategies can be applied to controls other than a pulse width modulation control.

[0084] Other devices can benefit from the control method of the invention, ...

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Abstract

The invention concerns a method of controlling a control circuit, which comprises a step in which a variation in a control parameter for the control circuit is effected, said variation being determined so that at least one emission characteristic of an unfavourable electromagnetic radiation is reduced.

Description

FIELD OF THE DESCRIPTION [0001] The present invention concerns a method of controlling a DC electric motor for reducing unfavourable radio-frequency emissions. BACKGROUND OF THE INVENTION [0002] The invention also concerns a vehicle lighting or signalling device of the type incorporating at least one control circuit generating unfavourable electromagnetic radiation and implementing the control method. [0003] In the motor industry, use is being made more and more of electric motors which, according to their operating phase and according to the control circuit which controls them, may emit a large quantity of radio-frequency signals whose effect is undesirable both on the safety of operation of the other electronic circuits of the vehicle and on the radio environment in which the vehicle is travelling. [0004] In particular, in the case of a stepping electric motor used for controlling the orientation of a lighting and / or signalling device, of the vehicle headlight type, it is necessar...

Claims

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Application Information

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Patent Type & AuthorityApplications(United States)
IPC IPC(8): H02P7/29H02M1/12H02M3/24H02P6/00H02P8/00H05K10/00
CPCH02P6/002H02P6/28
InventorFLANDRE, LOICBAUDRU, STEPHANBOUDIKIAN, DAVID
OwnerVALEO VISION SA